Eggs and sperm pass on environmental cues as well as genes

IN addition to matching up eye and hair colour, would-be-parents seeking eggs or sperm for IVF or surrogacy may run obesity, infection and stress checks on donors if current research patterns continue to hold true.

University of Adelaide scientists have published a review showing that rather than just being packages of genetic information, eggs and sperm also act as environmental messengers from generation to generation.

"The evidence shows that there is capacity for children to receive information about the conditions they are born into," said Professor Sarah Robertson, Director at The Robinson Research Institute and lead author on the paper.

"A woman's diet, body weight, obesity and age can all be all major determinants of the health trajectory of offspring created from a particular egg," she said.

"In men, age and obesity plus exposure to chemicals, drugs and alcohol modify the information that is transferred with sperm."

Studies of animal reproduction suggest that experiences such as stress, anxiety and infections can also create changes in eggs and sperm that alter the health of subsequent generations.

"We and others are now beginning to discover some pathways through which this experiential information is carried with eggs and sperm into embryos and offspring," said Professor Robertson.

While it is well known that the genes in eggs and sperm together provide the code that determines characteristics in each new individual, it is now clear that these other layers of influence - so-called epigenetic factors -are also at play.

Epigenetic transfer of environmental information is thought to occur through a variety of mechanisms, including how genes are packaged, where additional molecules are attached to genes and how small messenger molecules interact with genes.

Together, genes plus epigenetic factors from both eggs and sperm shape how the embryo and placenta develop, and also determine features of childhood and lifelong health.

Professor Robertson and her colleagues therefore propose that the responsibilities of parenting first start not when an embryo is conceived, but earlier - through creating healthy eggs and sperm.

The scientists aim to expand their research in this field, creating an evidence base for public health messages so that future parents have the best chances of conceiving robust offspring.

"Thinking about lifestyle factors and looking ahead to when you'd like to conceive is a way of supporting your child before she or he even exists," said Professor Robertson.

"Planning a pregnancy through mindful conception is like delivering a gift to your baby. And both men and women play a role," she said.

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